Device for treating bodily substances

ABSTRACT

A device for treating bodily substances, in particular for intraocular cataract surgery, said device comprising a laser beam source, for example, an erbium YAG laser, which produces pulsed laser radiation at wavelengths in the infrared range. A control device comprises a first arrangement ( 38, 48 ) by means of which an acceptable range for the pulse energy and/or pulse length and/or pulse frequency can be predetermined before an operation, and a second arrangement ( 34, 36, 40, 42 ) by means of which the pulse energy and/or pulse length and/or pulse frequency can be adjusted to a given value or values within the predetermined range during the operation.

The invention relates to a device for treating bodily substances,comprising a laser beam source which produces pulsed laser radiation atwavelengths particularly in the infrared range, an arrangement forguiding the laser radiation to the location of treatment, and furthercomprising a control device by means of which the pulse energy and/orpulse length and/or pulse frequency can be adjusted.

Quite generally, the invention is suitable for treating bodilysubstances, i.e. producing an effect on bodily substances in manydifferent ways. The term “treatment” may either refer to changing theconditions of these substances, or to removing these substances from thebody, or to changing the position of the substances in the body. Thebodily substances can be manifold, for example diseased tissue, or asubstance generated in diseased form, or tissue which is sound per sebut is to be removed for medical reasons. The following is a descriptionof the invention with regard to what is known as intraocular cataractsurgery.

A cataract is a change of the lens of the human eye, resulting in lossof transparency of the visible optical range of the lens. The region ofthe lens becomes cloudy. Loss of transparency causes impairment ofvision.

Cataract surgery refers to the surgical treatment of the cataract,wherein the cloudy lens is removed from the path of light beams requiredfor the optical perception. During the past centuries, such removal wasdone by what is known as cataract cracking, and the patient was thengiven so-called cataract lenses.

In 1949, the British ophtalmologist H. Ridley was the first to implantan artificial lens (PMMA) into the patient's eye after a cataractoperation.

Accordingly, before implanting an interocular (new) lens, cataractsurgery requires the original cloudy lens to be removed.

One criterion in cataract surgery recognised as being of growingimportance is the fact that as much neighboring tissue structures aspossible are to be maintained while the cloudy lens is being removed.

The surgical technique differentiates between the so-calledintracapsular lens dispensation and the extracapsular cataractextraction. In the last-mentioned method it is the aim of the operationto remove the cloudy lens from the capsule of the lens, with theintention to leave said capsule of the lens in its anatomic position asmuch as possible.

Lately, the so-called phacoemulsification has been developed as anexample for extracapsular cataract surgery (W. Böke“Phakoemulsifikation. Warum?”, Klin. Mbl. Augenheilk., 197 (1990)100-105, F. Enke publishing house of Stuttgart). Basically,phacoemulsification is a standard surgical operation performed by meansof a cut.

To reduce irritations of the tissue caused by cuts and othermanipulations of the tissue, the so-called ultrasonicphacoemulsification has lately been used to a larger extent (see JeffreyW. Berger, Jonathan H. Talamo, Keven J. LaMarche, Seon-Ho Kim, Robert W.Snyder, Donald J. D'Amico, George Marcellino “Temperature MeasuringDuring Phacoemulsification and Erbium: YAG Laser Phacoablation in ModelSystems”, Journal of Cataract Refract Surg., Vol. 22, April 1996, pp.372 to 378). Due to such ultrasonic phacoe-mulsification, both theinteroperative stresses as well as the postoperative complications maylargely be reduced to a minimum. By means of this technique, thematerial of the lens is removed via an aspiration/irrigation system. Theenergy used to crack the lens is caused by ultrasonic vibrations whichare applied to the body of the lens.

The energy required to crack the cloudy lens can also be provided bymeans of laser radiation (also see the above-mentioned article of J. W.Berger et al). In case of the so-called laser phacovaporization, forexample by means of Er- YAG- or Er-YSGG lasers, the material of the lensis broken, due to the high absorption of the laser radiation in the IRregion in the tissue to be treated, such cracking resulting in tissueablation or tissue separation (Ray P. Gailitis, Scott W. Patterson, MarkA. Samuels, Kerry Hagen, Qiushi Ren, George O. Waring “Comparision ofLaser Phacovaporization Using the Er-YAG and the Er-YSGG Laser”, ArchOphtamol, Vol. 111, May 1993, pp. 697-700).

The present invention relates to the removal of a cloudy lens by use oflaser.

Said above-mentioned problems do not only occur in cataract surgery butgenerally in treating substances of the human body (“bodily substances”)with laser radiation. When treating bodily substances with laserradiation it is generally important to treat only the diseased orchanged regions by means of such radiation, whilst more or less adjacentregions should at best not be exposed to such radiation.

U.S. Pat. No. 4,572,189 describes an electronic control device for asurgical laser system in which only the maximum pulse number and twopulse durations can be predetermined. U.S. Pat. No. 4,933,843 andEP-A-0164751 describe surgical laser systems in which unsatisfactoryadjustments of the system can be recognised by means of a menu control.

When used in cataract surgery, the invention relates to the technicalproblems arising from the different material of the lenses of differentpatients and from the non-homogeneity of the optical properties within alens, and it is the object of the invention to provide a device for theintraocular cataract surgery as mentioned in the beginning so that thesurgeon can be given a device which enables him to control theintraocular application of the laser energy to such an extent that itmay be possible for him to remove the cloudy lens carefully withoutimpairing the adjacent structures of the tissue.

According to the invention, this object relating to a device for theintraocular cataract surgery as mentioned above is solved in that thecontrol device comprises a first arrangement by means of which anacceptable range for the pulse energy and/or pulse length and/or pulsefrequency can be predetermined extent that the sound tissue remainsunafflicted to the utmost amount.

When used in cataract surgery, the invention relates to the technicalproblems arising from the different material of the lenses of differentpatients and from the non-homogeneity of the optical properties within alens, and it is the object of the invention to provide a device for theintraocular cataract surgery as mentioned in the beginning so that thesurgeon can be given a device which enables him to control theintraocular application of the laser energy to such an extent that itmay be possible for him to remove the cloudy lens carefully withoutimpairing the adjacent structures of the tissue.

According to the invention, this object relating to a device for theintraocular cataract surgery as mentioned above is solved in that thecontrol device comprises a first arrangement by means of which anacceptable range for the pulse energy and/or pulse length and/or pulsefrequency can be predetermined before an operation, and a secondarrangement by means of which the pulse energy and/or pulse lengthand/or pulse frequency can be adjusted to a given value or values withinthe predetermined range during the operation.

The invention is in particular also suitable for devices used indermatology, particularly for the treatment of scars or wrinkles. Whenused in dermatology, fibrous material or an articulated arm with mirroras known per se can also be used as guide means, i.e. the radiation isguided to the required location via mirrors.

Furthermore, the invention is also suitable for devices used indentology, in particular for the treatment of hard tooth substances suchas dental enamel or dentin.

When used in dentology, an Er:YAG solid-state laser is particularlysuitable as laser radiation source, and this preferably even incombination with another laser such as a Nd:YAG solid-state laser(wavelength: 1064 nm). It is preferred to use said two lasers inalternating manner via two different guide means, however, with the samecontrol device according to the invention being provided for pulseenergy, pulse length or pulse frequency.

The invention enables the surgeon to easily reduce the applied energy oflaser radiation drastically if, for example, the location of energysupply approaches a critical region, for example an adjacent tissuestructure like the capsular sac which should at best be preserved.Accordingly, the invention allows, on the one side, to adjust the energyof laser radiation respectively applied during the operation, dependingon the location where the laser radiation acts and on how far theoperation has proceeded and, on the other side, to restrict the pulseenergy and/or pulse length and/or pulse frequency which can be adjustedat all so that it can be ensured that only little energy or radiation ofundesired pulse length and/or pulse frequency is applied (e.g.inadvertently) during the operation.

Accordingly, the invention allows the operation to be done in efficient(especially fast) and controlled manner under controlled and monitoredenergy supply, while the surgeon can predetermine in advance anadmissible range for the pulse energy and/or pulse frequency and/orpulse length which can be adjusted at all in judging the material to betreated, e.g. the material of the lens, which appears to be optimal forthe material to be treated. During the operation (interoperative), thedesired parameters (pulse energy, pulse length or pulse frequency) mayimmediately be change by the surgeon by means of a simple handlingsystem such as an adjusting element which may either be actuated by handor by foot, depending on the stage of the operation and the materialjust being treated as well as on the location where the radiation acts.This enables the surgeon to react in definitely improved manner onindividual differences in the tissue of the lens during the operationand when he reaches adjacent of the tissue which are to be preserved.

Preferred embodiments of the invention are described in the dependentclaims.

An example of the invention for intraocular cataract surgery will beexplained in more detail by means of the drawings, in which:

FIG. 1 is a schematic view of a device for intraocular cataract surgery

FIG. 2 is a schematic view of a control device for intraocular cataractsurgery.

According to FIG. 1, a patient is placed on a bed 10. An anaesthetic anddiagnostic system was given reference number 12, and an OPMI (operationmicroscope) was given reference number 14. The surgeon sits on a chair16. A laser radiation source 19 is provided in a phaco ablation system18. The laser radiation source 19 is an erbium YAG-laser. The laseroutput radiation is transmitted to the patient's eye by means of a fibreoptics 21. This technique corresponds to the prior art and need not tobe explained in more detail.

The surgeon may either adjust the pulse energy and/or pulse lengthand/or particularly pulse frequency (pulse repetition frequency) bymeans of a foot-actuated switch 20.

FIG. 1 shows an aspiration and irrigation system 22 for removing thefragments of the lens. In addition to the aspiration and irrigationsystem 22, a monitor 24 (for example also a video) is provided for thesurgeon.

As concerns the control device 30 which has been integrated into thephaco ablation system 18, the key fields and functions with referencenumbers 32 to 48 as shown in FIG. 2 are here of special interest. Afield 32 shows different energy values for the adjustable pulse energy,viz. 10 mJ, 15 mJ, etc. to 100 mJ (pulse energy). Upper and lower limitsfor adjustable pulse energies can either be predetermined before anoperation in the “energy field” 32 via a keyboard (not shown in detail)or changed during an operation. These limits are shown in FIG. 2 inbrackets 38. Accordingly, said brackets 38 set the limits for admissibleadjustable pulse energy values which means that, in case of theembodiment shown in FIG. 2, the surgeon may adjust twenty to fifty mJpulse energy. The pulse energy may, for example, be changed during theoperation by means of the two keys 34, 36. As soon as the minimum pulseenergy value (20 mJ) has been set by the computer after havingdetermined the limit value 38, the surgeon may gradually increase thepulse energy to 25 mJ, 30 mJ, etc. by pressing the “+” key 36, whereineach respectively valid pulse energy value is emphasized, for example,by bright lightening of the pulse energy value respectively set.

Field 44 of the control device 30 shows adjustable pulse repetitionfrequencies, with frequencies of 10 to 100 Hz being gradually adjustableby the surgeon. Such adjustment is being done by means of the keys 40 or42 (increase or decrease of frequency). The device may optionally besuch that alternatively or additionally to the pulse energy range whichcan be adjusted before the operation (range limits 38) the pulserepetition frequency may also be adjusted in advance as concerns thefrequencies available at all, which is shown in FIG. 2 by bracket 48acting analogously with regard to the above-described bracket 38concerning the pulse energy.

The device comprises a so-called target beam to indicate the surgeon theposition of the non-visible IR laser beam. Such target beam may be, forexample, the beam supplied by a laser diode in the visible range (e.g.635 nm). The laser diode for the target beam is provided in the phacoablation system 18, and the radiation is also transmitted via the fibreoptics 21.

What is claimed is:
 1. A device for treating bodily substances,comprising a laser beam source (19) which produces pulsed laserradiation, guide means (21) for guiding the laser beam to the locationof treatment, and further comprising a control device (30) by means ofwhich at least one of the parameters selected from the group consistingof the pulse energy, pulse length and the pulse frequency can beadjusted, wherein said control device (30) comprises a first means (38,48) for predetermining, before an operation, an acceptable range for atleast one of the parameters selected from the group consisting of thepulse energy, the pulse length, and the pulse frequency, said rangehaving a minimum value different from zero, and said control device (30)comprising a foot switch (20) that can be actuated by a surgeon forquickly adjusting at least one parameter selected from the groupcomprising the pulse energy, the pulse length, and the pulse frequencywithin the predetermined range during the operation.
 2. A deviceaccording to claim 1, characterised in that an admissible range (38) canbe predetermined for the pulse energy by means of the control device(30) and in that a value within said predetermined range may optionallybe adjusted during the operation.
 3. A device according to claim 1,characterised in that an admissible range can be predetermined for thepulse repetition frequency by means of the control device and in that avalue within said predetermined range may optionally be adjusted duringthe operation.
 4. A device according to claim 1, characterised in thatlaser radiation is produced by the laser beam source in the infraredrange.
 5. A device according to claim 4, characterized in that laserradiation is produced by the laser beam source in the middle infraredrange.
 6. A device according to claim 1 for use in intraocular cataractsurgery, characterized in that said guide means (21) is designed in sucha manner that the laser radiation can be applied to ocular tissue.
 7. Adevice according to claim 1, characterised in that said guide means isdesigned in such a manner that the laser radiation can be applied totooth material.
 8. A device according to claim 1, characterised in thatthe laser radiation can be applied to skin by means of the guide means,wherein fiber material or an articulated arm with mirror is provided forsaid guide means.
 9. A device according to claim 1, characterized inthat the laser beam source is a solid-state laser doped with erbium. 10.A device according to claim 1, characterized in that the solid-statelaser source is an erbium YAG laser source.